[en] The Ghent State University disposes of 2 linear electron accelerator facilities: a 90 MeV low duty factor linac and a 15 MeV high beam power accelerator. Both facilities were initially designed in view of an extensive program of fundamental nuclear physics research. During some recent years a large effort has been devoted to the expansion of the field of machine applications. The accelerators have now evolved into versatile tools both for fundamental nuclear and solid state research, for medical therapy and radiation applications. The program and the necessary machine modifications and results are described with emphasis on original features: slow positron production and transport, high power electron beam handling and bremsstrahlung target design, radiation processing equipment and a high gamma dose setup for extracorporeal irradiation in bone tumors therapy

[en] The use of electron accelerators in industry involves a broad range of machines and applications. The major actual large-scale applications are crosslinking of wire and cable insulation, plastic films and foam, curing of coatings and rubbers, and sterilisation of medical products. The recent availability, at attractive costs, of electron accelerators with high beam power (up to 200 kW) covering an energy range up to 10 MeV, has created new possibilities for a substantial expansion of the application range. The actual position of electron accelerators in industry is reviewed, new emerging applications and novel opportunities for multipurpose facilities are described. (orig.)

[en] The Gent University 15 MeV 20 kW linear electron accelerator facility was initially designed for fundamental nuclear physics research. During the last year a large effort has been devoted to the expansion of the range of machine applications in view of a new extensive experimental programme in the fields of atomic and solid-state physics, biomaterials research, polymer chemistry, space research, food technology, high-dose dosimetry and radiation therapy. The accelerator has now evolved into a versatile tool delivering electron and gamma beams with a wide variety of characteristics (intensity covering a range of 12 orders of magnitude, variable energy, repetition rates and pulse dose rates, pencil and broad beams, irradiations under different temperatures and environmental atmospheres). The accelerator facility, the peripheral equipment, the experimental programme and first results are described with emphasis on the original features

[en] A non-destructive analysis of the distribution of heavy elements in samples can be performed using tunable gamma-ray sources. By scanning a sample using photons having two energies, one just below and one just above the K-edge of the element under study, the reconstructed distribution becomes only sensitive to this element. Here we show that the distribution of a sample containing several heavy elements can be reconstructed element by element. We also study how far the method can be made quantitative

[en] The work we present consists of the development of a computerised 3-D scanning system running under LABVIEW[reg]. 3-D magnetic field measurements, form an important application allowing a fast on-line determination of charged particle trajectories in real magnetic fields. The set-up consists of a Hall-probe, movable in three dimensions, mimicking a charged particle entering a magnetic field with well-defined transport characteristics (energy, position, momentum). The measured local field components are used as input to a LABVIEW[reg] program, which calculates the local direction of the flight-path of the particle. Then the probe is moved along this direction with a predetermined step-length. In this way, the real path of the charged particle is determined step by step automatically accounting for all magnetic field imperfections. Trajectories can be determined without the measurement of the whole 3-D field configuration

[en] The X-ray attenuation coefficients of bismuth and of uranium were measured in the regions of 40-240 and 70-240 keV, respectively, using a tuneable hard X-ray source based on the linear electron accelerator at the University of Ghent. Results were compared with the semi-empirical values of Storm and Israel and to the theoretical values of Berger and Hubbell. We also propose a simple function for the attenuation coefficient in the vicinity of the K-edge for uranium and in an extended range of energy for bismuth. The set-up of the source at Ghent is described and the future improvements are explained.

[en] The Gent University has a high beam intensity 1.5-15 MeV linear electron accelerator, built primarily for multidisciplinary research with electron and gamma beams. The linac has to deliver, continuously over the whole energy range, intense high quality beams, providing radiation pulses with a wide variety of characteristics (variable repetition rate, pulse length and pulse dose, etc.), but with a high degree of stability and reproducibility. The regulation and control systems necessary to optimise the output of the accelerator are described with regard to the underlying design philosophy and with emphasis on several new implemented features. The resulting performance and operational experience are analysed. (orig.)

[en] The effectiveness of X-radiation on regeneration of adventitious buds on in vitro leaf explants of three Rosa hybrida L. genotypes was studied. In vitro leaflet explants of roses produced adventitious buds when cultured in the dark for 1 week on Murashige and Skoog (MS) induction medium containing 6.8 μM thidiazuron (TDZ) + 0.49 μM indole-3-butyric acid (IBA) and subsequently transferred to MS regeneration medium containing 2.2 μM benzyladenine (BA) + 0.049 μM IBA in the presence of reduced light, at 15 μmol m^-2 s^-1 photosynthetically active radiation (PAR). Analysis of radiosensitivity by irradiating leaf explants with increasing doses of X-rays between 25 and 100 Gray (Gy) resulted in a decreasing rate of leaf explants regenerating buds from 47% to 0% respectively. The lethal dose for 50% of the regenerating explants (LD₅₀) in all the three genotypes was estimated to be 25 Gy at a dose rate 2 Gy/s. For the main experiment, doses of 5 and 15 Gy were selected and variations were observed between genotypes. Clone RUI 317 had the highest rate of adventitious bud regeneration, with 83.6% (2.5 buds/explant) at 5 Gy and 64% (1.8 buds/explant) at 15 Gy, compared to 89% (3.4 buds/explant) with the untreated control. Significant differences in the percentage of bud regeneration of the three genotypes were only observed at 15 Gy in comparison to the control and the number of buds formed per regenerating explant varied between 1 to 4. (author)

[en] An experimental set-up for the production of monochromatic X-ray beams tunable in the energy region between 40 and 700 keV was built at our facility. This paper describes the design of a Bremsstrahlung radiator to create a suitable photon field for monochromatisation by Laue diffraction on a curved single-crystal. (author)

[en] Since the appearance of high flux neutron beams, scientists experimented with neutron radiography. This high beam flux combined with modern neutron to visible light converters leads to the possibility of performing fast neutron micro-tomography. The first results of cold neutron tomography with a neutron lens are presented in this article. Samples are rotated in the beam and the projections are recorded with a neutron camera. The 3D reconstruction is performed with cone beam reconstruction software.